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  <div class="section" id="s-postgresql-specific-database-functions">
<span id="postgresql-specific-database-functions"></span><h1>PostgreSQL specific database functions<a class="headerlink" href="#postgresql-specific-database-functions" title="Permalink to this headline">¶</a></h1>
<p>All of these functions are available from the
<code class="docutils literal notranslate"><span class="pre">django.contrib.postgres.functions</span></code> module.</p>
<div class="section" id="s-randomuuid">
<span id="randomuuid"></span><h2><code class="docutils literal notranslate"><span class="pre">RandomUUID</span></code><a class="headerlink" href="#randomuuid" title="Permalink to this headline">¶</a></h2>
<dl class="class">
<dt id="django.contrib.postgres.functions.RandomUUID">
<em class="property">class </em><code class="descname">RandomUUID</code><a class="reference internal" href="../../../_modules/django/contrib/postgres/functions.html#RandomUUID"><span class="viewcode-link">[source]</span></a><a class="headerlink" href="#django.contrib.postgres.functions.RandomUUID" title="Permalink to this definition">¶</a></dt>
<dd></dd></dl>

<p>Returns a version 4 UUID.</p>
<p>The <a class="reference external" href="https://www.postgresql.org/docs/current/pgcrypto.html">pgcrypto extension</a> must be installed. You can use the
<a class="reference internal" href="operations.html#django.contrib.postgres.operations.CryptoExtension" title="django.contrib.postgres.operations.CryptoExtension"><code class="xref py py-class docutils literal notranslate"><span class="pre">CryptoExtension</span></code></a> migration
operation to install it.</p>
<p>Usage example:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="gp">&gt;&gt;&gt; </span><span class="kn">from</span> <span class="nn">django.contrib.postgres.functions</span> <span class="k">import</span> <span class="n">RandomUUID</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">Article</span><span class="o">.</span><span class="n">objects</span><span class="o">.</span><span class="n">update</span><span class="p">(</span><span class="n">uuid</span><span class="o">=</span><span class="n">RandomUUID</span><span class="p">())</span>
</pre></div>
</div>
</div>
<div class="section" id="s-transactionnow">
<span id="transactionnow"></span><h2><code class="docutils literal notranslate"><span class="pre">TransactionNow</span></code><a class="headerlink" href="#transactionnow" title="Permalink to this headline">¶</a></h2>
<dl class="class">
<dt id="django.contrib.postgres.functions.TransactionNow">
<em class="property">class </em><code class="descname">TransactionNow</code><a class="reference internal" href="../../../_modules/django/contrib/postgres/functions.html#TransactionNow"><span class="viewcode-link">[source]</span></a><a class="headerlink" href="#django.contrib.postgres.functions.TransactionNow" title="Permalink to this definition">¶</a></dt>
<dd></dd></dl>

<p>Returns the date and time on the database server that the current transaction
started. If you are not in a transaction it will return the date and time of
the current statement. This is a complement to
<a class="reference internal" href="../../models/database-functions.html#django.db.models.functions.Now" title="django.db.models.functions.Now"><code class="xref py py-class docutils literal notranslate"><span class="pre">django.db.models.functions.Now</span></code></a>, which returns the date and time of the
current statement.</p>
<p>Note that only the outermost call to <a class="reference internal" href="../../../topics/db/transactions.html#django.db.transaction.atomic" title="django.db.transaction.atomic"><code class="xref py py-func docutils literal notranslate"><span class="pre">atomic()</span></code></a>
sets up a transaction and thus sets the time that <code class="docutils literal notranslate"><span class="pre">TransactionNow()</span></code> will
return; nested calls create savepoints which do not affect the transaction
time.</p>
<p>Usage example:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="gp">&gt;&gt;&gt; </span><span class="kn">from</span> <span class="nn">django.contrib.postgres.functions</span> <span class="k">import</span> <span class="n">TransactionNow</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">Article</span><span class="o">.</span><span class="n">objects</span><span class="o">.</span><span class="n">filter</span><span class="p">(</span><span class="n">published__lte</span><span class="o">=</span><span class="n">TransactionNow</span><span class="p">())</span>
<span class="go">&lt;QuerySet [&lt;Article: How to Django&gt;]&gt;</span>
</pre></div>
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<li><a class="reference internal" href="#">PostgreSQL specific database functions</a><ul>
<li><a class="reference internal" href="#randomuuid"><code class="docutils literal notranslate"><span class="pre">RandomUUID</span></code></a></li>
<li><a class="reference internal" href="#transactionnow"><code class="docutils literal notranslate"><span class="pre">TransactionNow</span></code></a></li>
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